As the use of digital data increases, the demand for faster, smaller, and more efficient memory structures increases. One type of memory structure that has recently been developed is a crossbar memory structure. A crossbar memory structure includes a first set of conductive lines that intersect a second set of parallel conductive lines. A programmable memory element configured to store digital data is placed at each intersection of the lines.
One type of programmable memory element which may be used is a memristive element. A memristive element is a device which changes the state of its resistance based on an applied programming condition. For example, a programming condition may be applied to change the memristive element from a high resistive state to a low resistive state or vice versa. A high resistive state may represent a digital “1” and a low resistive state may represent a digital “0”.
One challenge that results from use of a crossbar memory structure is the process of reading the state of a target memory element. The state of a memory element may be determined by applying a read voltage on one side of the target memory element. The voltage measured by a sense element on the other side of the target memory element will be indicative of the state of the target memory element. However, when applying a read voltage to a target memory element, the current sensed by the sensing circuitry includes current flowing through as well as currents flowing through unselected and half-selected memory elements within the crossbar array. Thus, it is difficult to isolate the current flowing through the target memory element that is a direct result of the applied read voltage.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.